Jack-up rig

The jack-up arrives floating, towed or self-propelled, then lowers its legs to the seabed and raises its hull out of the water so the waves pass beneath. It suits shallow water, down to about a hundred meters for most and a little more for recent units. Its signature loss is punch-through: the ground under a leg gives way all at once, the platform tilts, sometimes to the point of total loss. The counter is preloading: the unit is filled with ballast water before drilling to test the soil. It does not replace a geotechnical study of the site, the first document the underwriter asks for. Two other losses recur. Towage, when the jack-up is moved with legs raised and a high center of gravity, and a storm catches it en route; policies set weather and tug certification conditions, and a loss in transit is not settled like a loss on location. And interaction with a neighboring fixed platform, when the unit is set down beside existing infrastructure. Insurance splits between the hull, the drilling contractor's liability and, if the well is involved, the operator's policy. The loss rate runs higher than for semi-submersibles, hence rate loadings for this class of unit.